This invention relates to an improved method and apparatus for processing sonar pulse code echoes for determining the doppler of a return echo.
A known prior art approach for processing sonar pulse codes for determining the doppler of such return echo is the use of a complex of parallel filter channels. One filter channel is needed for each desired increment of doppler determination. An example of such a system is disclosed in U.S. Pat. No. 3,302,162, R. O. Rowlands, entitled "Doppler Sonar Apparatus". The complexity and size of filter bank structure which would be needed to provide a large multiplicity of channels make this approach impractical for fine doppler resolution applications.
Accordingly, the objectives of the invention include provision of:
(1) An improved method and apparatus for processing sonar pulse code echoes to determine the doppler of a return echo with a high degree of resolution. PA1 (2) An improved method and apparatus in accordance with the preceding objective which is further adaptable to operate in a mode of operation providing range determination with a high degree of resolution. PA1 (3) An improved method and apparatus for processing sonar pulse code echoes in accordance with the preceding objective, and which may be implemented by a construction which is sufficiently compact for use in the smaller type acoustic torpedoes, such as are launched from aircraft.
Other objects and many of the attendant advantages of this invention will be readily appreciated as it becomes better understood by reference to the description and accompanying drawing which follows.